Algal Bloom and Trotsky Drive

[GiulioGratz]

Hi, a friend of mine asked me a fuzz with switchable pre gain and clean mix.

I tried to put together theese circuits:
PRE GAIN: trotsky drive (schematic from this forum) with 2n3904 transistor and red led clipping diodes;
FUZZ: fuzzhugger algal bloom (schematic from tagboardeffects http://tagboardeffects.blogspot.it/2016/02/fuzzhugger-algal-bloom.html );
then i made the clean mix section in this way:
TL072 non inverting buffer (from http://www.experimentalistsanonymous.com/diy/Schematics/Buffers%20Switchers%20Mixers%20and%20Routers/Op%20amp%20noninverting%20buffer%203.gif ) that sends the "pre gained" signal to a volume pot (100k log);
TL072 mixer (copied from "space and time reverb" found in this forum) with inputs from algal bloom and buffer and output to the output jack.

With all the circuits soldered:
Algal bloom without trotsky drive in front: it has some problems, if i touch the pots with starve or bloom at "non zero" there is a squealing noise (ground problem???); and transistors seem to apply a treshold on the signal (small signals decay very very quickly).
Algal bloom with trotsky drive activated in front: volume dropped at something near zero even with trotsky volume pot at max.
Clean mix circuit: doesn't work at all; the clean volume pot have a range of work: at minimun it kills also the fuzz signal; in range squeals.

Are there incompatibilities between the circuits? Impedences mismatch? Wrong way to do what i want?

Uh, voltages aren't so bad: tl072 polarized correctly in both buffer and mixer parts; algal bloom's transistors have voltages comparable with those of other people on another forum; LEDs on the trotsky aren't smoked.

Any advice?

Thank you very much
GiulioGratz